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TUBE questions:

#2
How can i know if a tube is dying?

If the power tubes start to go, you will lose volume, and the tone will be terrible. Preamp tubes can go microphonic and start to make noise, or simply die and you may lose all sound.

Where can i get information on the bias thing and how to set it?

There is a ton of information on the web, and you can order a Weber Biasrite to simplify things, but be careful. Poking around in an amp can be dangerous, and it's required that you drain the caps of any residual electricity to assure you won't get shocked.


Are tubes plug and play (leaving the BIas apart)?

Preamp tubes are, but for power tubes it depends on the circuit, and you may want to check with the company that built the amp.
 
#4
fireincairo said:
How can i know if a tube is dying?

If the power tubes start to go, you will lose volume, and the tone will be terrible. Preamp tubes can go microphonic and start to make noise, or simply die and you may lose all sound.

Where can i get information on the bias thing and how to set it?

There is a ton of information on the web, and you can order a Weber Biasrite to simplify things, but be careful. Poking around in an amp can be dangerous, and it's required that you drain the caps of any residual electricity to assure you won't get shocked.


Are tubes plug and play (leaving the BIas apart)?

Preamp tubes are, but for power tubes it depends on the circuit, and you may want to check with the company that built the amp.
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B-string said:
Also not all fixed Bias amps are readily adjustable, they require componet replacement to re-bias. In short if you need to ask, have an amp tech do it till you learn a lot more including the safety procedures. You'll live to make music that way.
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Thx a lot guys, im not going to do anything, i was just curious about this things cos i keep hearing things like biasing amps and stuff and never really knew why ppl keep telling others that it should be done by a tech.
 
#6
wallybill said:
There are high powered caps inside the amp. If they aren't properly discharged and you touch something connected to those caps while your other hand is on the chassis = instant high voltage circuit with your heart in the middle of it.
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Yes i knew this, not amp wise, but Ive seen it done in other household machinery.

But my concern was abaout biasing being something that can actually perm damage your amp (preamp in my case) if done wrong.

BTW being halfway through my engineering degree this kind of information has become really appealling to me recently.
 
#8
vene-nemesis said:
Yes i knew this, not amp wise, but Ive seen it done in other household machinery.

But my concern was abaout biasing being something that can actually perm damage your amp (preamp in my case) if done wrong.
Click to expand...
It can if the bias is off enough to cause your amp to overheat. Not in a preamp, though. You can change tubes in a preamp all day long.
 
#9
vene-nemesis said:
BTW being halfway through my engineering degree this kind of information has become really appealling to me recently.
Click to expand...

Preamp tubes are self-bias so no worries. Output tubes require a bias setting to the individual tube (and tube type) in most all cases. You need to adjust for a point where the tube is conducting at no signal "negative bias"(above cut-off, but can be adjusted to "cold") but not high enough that the tube reaches saturation to early with the applied signal "Bias to far towards positive"(biased to hot).
 

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